Filmmaker and conservative activist known for embarrassing and politically-loaded hidden-camera videos. He made a series of videos inside Planned Parenthood offices in 2006 and 2007 with activist Lila Rose, who founded the anti-abortion group Live Action when she was 15 years old. In the videos, Rose, who was then 20, pretended to be 13 and pregnant by a 31-year-old man. Instead of reporting the cases to police, as required by law, the tapes show that some Planned Parenthood staffers advised Rose about how to get an abortion.

More famously, in 2009 O'Keefe made a series of videos targeting the Association of Community Organizations for Reform Now (ACORN). Accompanied by 20-year-old Hannah Giles (daughter of conservative minister Doug Giles), O'Keefe travelled across America and visited ACORN offices in numerous cities, pretending to be involved in absurd or illegal activity. He was dressed in an outlandish "pimp" costume for footage filmed outside ACORN offices (though he wore much more ordinary outfits when speaking with ACORN staff). Edited versions of the video were released through Andrew Breitbart's right-wing website biggovernment.com, and ACORN workers' calm or cooperative responses to Giles and O'Keefe's bizarre inquiries were deemed scandalous and heavily hyped on Fox News. In the aftermath, some ACORN employees were fired, and the group, which had advocated for low-income workers and led nationwide voter-registration drives, was defunded by Congress and largely disbanded. Investigators, however, have concluded that the videos show no illegal activity by ACORN employees.

O'Keefe was arrested in New Orleans on 25 January 2010 with three other men for "entering federal property under false pretenses" in what was apparently an attempt to wiretap the office of Senator Mary Landrieu (D-Louisiana). Two of the men arrested with O'Keefe were disguised as telephone repair workers, wearing overalls, fluorescent vests, tool belts and hard hats. All four men pleaded guilty to entering US property under false pretenses.

In September 2010, it was reported that CNN reporter Abbie Boudreau had arranged an interview with O'Keefe, but canceled after the network obtained a bizarre 13-page document describing O'Keefe's intent to turn the interview into an elaborate prank. Titled "CNN Caper", the paper detailed a plan to relocate the interview onto a boat, which was to be stocked with dildos, handcuffs, pornography, hidden cameras, and "an obvious sex tape machine" near a bed. Scripted dialogue called for O'Keefe to say, "I'm going to seduce her, on camera, to use her for a video. This bubble-headed-bleach-blonde who comes on at five will get a taste of her own medicine, she'll get seduced on camera and you'll get to see the awkwardness and the aftermath."

In 2010, O'Keefe established Project Veritas, to "investigate and expose corruption, dishonesty, self-dealing, waste, fraud, and other misconduct in both public and private institutions in order to achieve a more ethical and transparent society." Other O'Keefe/Project Veritas videos have targeted Hillary Clinton's 2016 Presidential campaign, the New Jersey Education Association, Medicaid offices in six states, National Public Radio, and purported voter fraud in New Hampshire.
In a 2014 stunt, O'Keefe wore green fatigues and an Osama bin Laden costume and snuck across the United States border to Mexico, then back into Texas, all on video which he then released to show that the border is far from secure. In a bit of unexpected blowback, however, the Dept of Homeland Security was not amused by O'Keefe's illegal border crossing, and his name was placed on a list of persons meriting extra scrutiny at Customs. He has since complained that now he feels unjustly targeted by DHS, leading to delays and extended inquiries every time he (legally) enters the U.S.A.

O'Keefe and Project Veritas continue making "sting" videos, which continue to receive enthusiastic coverage at Fox News and other right-wing media outlets.